Work function variation during UV laser-induced oxide removal

Photocurrent measurements yielded new data, which were used to determine th e surface work function of a native oxide-covered tungsten photocathode. Th e photoemission was generated by a continuous UV source, The surface work f unction has been measured at various stages of a pulsed UV laser-induced ox ide removal in order to characterize the process. Since the measured surfac e work function can be correlated with the surface coverage, along with the measurements of charge of laser-induced photoelectrons a description of th e laser-oxide interaction is presented. A fully computer-controlled experim ental setup is demonstrated, achieving photoelectric measurements at the sp ot of laser illumination. This apparatus enables us to follow the work func tion temporal dependence during laser illumination, thus giving a detailed description for the surface coverage dynamics. (C) 1999 Elsevier Science B. V. All rights reserved.